The present invention relates to apparatus for transporting particulate materials, especially shreds or otherwise configurated fragments of tobacco including natural, reconstituted and substitute tobacco.
It is well known to transport a continuous or an interrupted flow of shredded or otherwise comminuted tobacco leaves, comminuted sheets of reconstituted tobacco and/or fragments of substitute tobacco in a gaseous carrier medium (normally air) which conveys the particles from a suitable source into the distributor of a cigarette rod making or other tobacco processing machine. It is also known to equip such apparatus with an air separator which segregates the transported particles from the carrier medium. As a rule, the air separator has a first chamber which receives the carrier medium and the particles therein, and a second chamber which is separated from the first chamber by an air-permeable partition and is connected with the inlet of a suction generating device. This ensures that the conveyed particles are collected in the first chamber and that the carrier medium is withdrawn by way of the partition and second chamber. It is further known to install an adjustable flow restrictor in the inlet of the suction generating device. The air separator has an outlet which can be actuated to admit batches of intercepted tobacco particles into the distributor of a cigarette rod making machine. The outlet is actuated in dependency on the requirements of the distributor so that the magazine of the distributor (also called hopper) contains an optimum quantity of comminuted tobacco particles. It is desirable that the magazine of the distributor be filled to a predetermined level and that the particles of tobacco be prevented from accumulating into clumps (e.g., into aggregations of interlaced tobacco shreds) which would be likely to interfere with the making of a homogoneous tobacco filler having predictable characteristics and being convertible into a satisfactory tobacco rod.
An apparatus which transports particles of natural, artificial or reconstituted tobacco to a processing machine (e.g., to a cigarette, cigarillo or cigar maker) must satisfy numerous additional requirements in order to further enhance the likelihood of making a highly satisfactory tobacco filler which is ready to be draped into a web of cigarette paper or other wrapping material for conversion into a continuous rod which is thereupon subdivided into sections of unit length or multiple unit length. Thus, the consistency of tobacco particles (such as the length and other characteristics of shreds) as well as the mixture of particles (e.g., the mixture of shorter and longer shreds or the mixture of two or more different tobacco blends) should not be adversely or overly affected by the gaseous carrier medium which is used to transport the particles from a main source of supply into the air separator. Moreover, if the characteristics of conveyed material are to be changed or influenced, such changing or influencing should be carried out in a highly reproducible manner. The velocity of the gaseous carrier medium in the pneumatic conveyor which transports the particles of tobacco from the main source into the first chamber of the air separator is a parameter which plays an important role in the operation of pneumatic tobacco transporting apparatus. The velocity of the gaseous carrier medium must be selected in such a way that it reduces the likelihood of or eliminates adverse influence of the carrier medium upon the consistency of tobacco particles while, at the same time, ensuring that the distributor of a modern high-speed tobacco processing machine (e.g., a cigarette maker which turns out up to and in excess of 8000 cigarettes per minute) receives adequate quantities of comminuted tobacco.